Preliminary evaluation of serum iron and TIBC as screening markers in suspected tuberculosis

Introduction

Infectious diseases like tuberculosis (TB) continue to be a major health problem around the world, especially in less developed regions. Early identification of tuberculosis remains challenging in resource-constrained settings owing to vague clinical presentation and limited access to advanced diagnostic facilities. This is despite the availability of efficient diagnostic instruments and treatment regimens. Transmission, disease progression, and fatality rates are all worsened when diagnoses are delayed [1,2] . As a chronic inflammatory disease, tuberculosis drastically changes the way the host body uses iron. Mycobacterium development and host immunological defense both rely on iron. The reticuloendothelial system sequesters iron during persistent illnesses like tuberculosis, resulting in low serum iron levels circulating in the blood. The process by which inflammatory cytokines and elevated hepcidin synthesis hinder iron absorption in the intestines and iron release from macrophages is what causes this syndrome, which is often called anemia of chronic illness [3][4][5] . Inflammatory conditions also impact total iron-binding capacity (TIBC), which is an indirect indicator of transferrin levels. Reduced hepatic production of transferrin is one reason why TB patients typically have lower TIBC levels, which in turn affect iron homeostasis. The inflammatory load and disease activity are reflected in these variations in serum iron and TIBC [6,7] . While sputum microscopy, cultures, and nucleic acid amplification tests are widely recognized as the gold standard for tuberculosis diagnosis, these technologies aren't always accessible or provide fast findings. Thus, there is a great deal of clinical interest in developing simple and cost-effective laboratory criteria to aid in early screening. The current study was conducted to assess the potential screening markers of serum iron and TIBC in patients suspected of having tuberculosis [8][9][10] .

Materials and Methods

This was a prospective observational study carried out in the Department of Medicine in conjunction with the Department of General Medicine, Sri Lakshmi Narayana Institute of Medical sciences, Agaram Village, Villianur Commune, Kudupakkam Post, Puducherry, between September 2018 to August 2019. During the trial period, 40 individuals with a clinical suspicion of tuberculosis were included after providing informed consent. Patients exhibiting symptoms indicative of tuberculosis, including chronic cough, fever, weight loss, night sweats, and radiological abnormalities consistent with TB, were assessed. The Institutional Ethics Committee gave its approval for the study.

Inclusion Criteria

Statistical Analysis

Application software known as Statistical Package for the Social Sciences (SPSS) was used for data entry and analysis. The mean plus or minus the standard deviation (SD) was used to represent continuous variables. The levels of serum iron and TIBC were compared between the groups with and without proven tuberculosis using an independent t-test. A statistically significant result was defined as a p-value less than 0.05.

Results

The study comprised 40 participants who were clinically suspected of having tuberculosis. Based on microbiological and/or radiological confirmation, 22 patients (55%) were diagnosed with tuberculosis, while 18 patients (45%) were categorized as non-tuberculosis cases. Every subject had the necessary tests and was incorporated into the final analysis. In comparison to patients without tuberculosis, those with confirmed cases were more likely to have constitutional symptoms such persistent coughing, fever, and decreased weight. There appears to be a change in iron metabolism in active tuberculosis, since the tuberculosis group had substantially lower mean serum iron levels than the non-TB group. This suggests that inflammation-related reduction of transferrin synthesis is at work in tuberculosis patients, as their TIBC levels are markedly lower than those of non-TB patients. A significant number of tuberculosis patients (81.8%) had lower serum iron and total iron binding capacity (TIBC) than non-TB patients, indicating that these markers could be useful as additional screening tools for suspected tuberculosis.

Discussion

Changes in iron homeostasis are among the many metabolic and immunological changes brought about by tuberculosis, a long-term infectious disease. This study looked at serum iron and total iron-binding capacity (TIBC) as possible screening markers for tuberculosis in patients who might have the disease. It found that low levels of both parameters were associated with active tuberculosis [11,12] . Serum iron levels were found to be considerably lower in people with proven tuberculosis compared to those without the disease. In the well-known anemia of chronic disease, inflammatory cytokines cause an increase in hepcidin synthesis, which in turn causes iron to be sequestered inside macrophages and less available in the bloodstream. This data is in line with that theory. As a host defensive mechanism, iron redistribution is thought to reduce the availability of iron to Mycobacterium tuberculosis [13][14][15] . Patients with tuberculosis also had substantially lower TIBC values. When inflammation persists over an extended period of time, the liver produces less transferrin, which shows in a lower TIBC. This study's findings that most TB patients had decreased blood iron and total iron binding capacity (TIBC) provide credence to the idea that these parameters might be used as indirect indicators of disease activity, drawing attention to the inflammatory nature of tuberculosis [16][17][18] . There is strong evidence to support the use of serum iron and TIBC as supplementary screening techniques, as more than 80% of confirmed tuberculosis cases showed a simultaneous drop in both. In resource-limited situations, where access to advanced diagnostic modalities may be restricted, these parameters can be especially beneficial due to their widespread availability, low cost, and simplicity of evaluation; nevertheless, they are not disease-specific [19,20] .

It is important to consider the study's limitations before interpreting its results, though. It is difficult to draw firm conclusions about cause and effect because of the study's observational approach and the tiny sample size. We also did not evaluate inflammatory indicators like C-reactive protein or hepcidin levels, and we excluded additional inflammatory disorders that may impact iron metabolism based on clinical criteria alone. To further understand iron metabolism in tuberculosis, future research should use bigger cohorts and more biomarkers [21,22] . This preliminary study's findings, taken as a whole, provide more evidence that serum iron and TIBC levels are indicators of disease-related inflammatory alterations in tuberculosis and could be valuable additions to the initial screening of suspected cases [23,24] .

Conclusion

Serum iron and total iron-binding capacity (TIBC) levels are considerably lower in tuberculosis patients compared to non-TB individuals, according to this study. These parameters were found to be reduced in most tuberculosis cases, which is consistent with the iron metabolism changes seen in chronic inflammatory conditions. Initial evaluation of patients with suspected tuberculosis, especially in resource-limited settings, may benefit from the use of serum iron and TIBC as additional screening markers. These laboratory procedures are straightforward, affordable, and widely available. Clinical findings and conventional diagnostic tests should be considered with these characteristics because they are not disease-specific. These findings need to be validated and their use in illness monitoring and treatment response investigated in further large-scale trials.

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